Hi Charlie, Water parks may be cleaned with soap and water, or up to 10% bleach solution (only as needed) For further info, please see our care article here: http://www.blastzone.com/articles/Caring-for-Inflatable-Water-Parks/ Water parks are not meant to hold any substantial water, and do not retain water overnight. However, for further tips on saving water, please see the below article. The biggest tip is simply to turn the hose spigot down to use as little spray as absolutely necessary. The Pirate Bay has a substantial splash area, and it's great to hear your commitment to minimizing water use. We don't recommend leaving inflatables outside for any prolonged period. http://www.blastzone.com/articles/Minimize-Water/ Sincerely, Blast Zone Support